Different Expressions of Pericardial Fluid MicroRNAs in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy and Ischemic Heart Disease Undergoing Ventricular Tachycardia Ablation

Introduction: Pericardial fluid is enriched with biologically active molecules of cardiovascular origin including microRNAs. Investigation of the disease-specific extracellular microRNAs could shed light on the molecular processes underlying disease development. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart disease characterized by life-threatening arrhythmias and progressive heart failure development. The current data about the association between microRNAs and ARVC development are limited.

Methods and Results: We performed small RNA sequence analysis of microRNAs of pericardial fluid samples obtained during transcutaneous epicardial access for ventricular tachycardia (VT) ablation of six patients with definite ARVC and three post-infarction VT patients. Disease-associated microRNAs of pericardial fluid were identified. Five microRNAs (hsa-miR-1-3p, hsa-miR-21-5p, hsa-miR-122-5p, hsa-miR-206, and hsa-miR-3679-5p) were found to be differentially expressed between patients with ARVC and patients with post-infarction VT. Enrichment analysis of differentially expressed microRNAs revealed their close linkage to cardiac diseases.

Conclusion: Our data extend the knowledge of pericardial fluid microRNA composition and highlight five pericardial fluid microRNAs potentially linked to ARVC pathogenesis. Further studies are required to confirm the use of pericardial fluid RNA sequencing in differential diagnosis of ARVC.

[The Efficiency of Immunoprecipitation of microRNA/Ago2 Complexes from Human Blood Plasma Is Protocol Dependent]

The study of extracellular miRNA is one of the most dynamic areas of modern biomedical research. Oftentimes, there is a need to isolate miRNAs associated with a particular carrier, for example, a ribonucleoprotein complex. The most thoroughly investigated protein component of these complexes is Ago2. Complexes are commonly isolated by immunoprecipitation with specific antibodies. Here we compare three methods for immunoprecipitating Ago2/microRNA complexes from blood plasma. In the first protocol, anti-Ago2-antibodies are added to the plasma following protein A-sepharose. In second protocol, anti-Ago2-antibodies are bound to sepharose from the very beginning, and then mixed with plasma. The third protocol differs from the second in that sepharose is blocked by non-specific antibodies at the final stage. To compare the efficiency of these protocols, the levels of miR-16-5p, miR-21-5p, and miR-144-3p were analyzed after precipitation with anti-Ago2 antibodies and control antibodies. For miR-16-5p all protocols were efficient, for miR-21-5p only the second technique yielded results, while for miR-144-3p none of the protocols resulted in extraction. Thus, we conclude that different protocols for immunoprecipitation of microRNA/Ago2 complexes favor different miRNAs.